Pelvis and Perineum Flashcards
What divides the pelvis into the greater and lesser pelvis
Pelvic brim
Pelvic diaphragm
bowl shaped sheet of skeletal muscle that forms the floor of the pelvis and room of the perineum.
Bones that form the pelvic girdle
lef and right coxal bones, and sacrum
Sacral hiatus
created by the lamina of the S5 vertebrae not fusing
Ala of sacrum articulate with what?
They articulate laterally with the posterior surface of a coxal bone.
Which one is larger anterior or posterior sacral foramina?
Anterior.
Sacro-iliac joint
composed of sacrum and coxal bones
What 3 bones form the coxal bone?
ilium, ischium, and pubis
what forms the ischiopubic rams?
Ramus of ischium and inferior pubic ramus.
Where does the sacrospinous ligament attach
ischial spine and sacrum.
Where does the sacrotuberous ligament attach
ischial tuberosity and sacrum
What divides the Sciatic foramen into the greater and lesser sciatic foramen
the sacrospinous ligament
What divides the greater sciatic foramen
Piriformis muscle
What structures exit the greater sciatic foramen?
Piriformis, superior and inferior gluteal nerves, arteries, and veins, sciatic nerve, internal pudendal vessels, pudendal nerve.
Basically structures that exit lesser pelvis and enter gluteal region and posterior thigh.
What structures exit the lesser sciatic foramen
Internal pudendal vessels, pudendal nerve, tendon of obturator internus
basically structures leaving pelvis and going to perineum
Which part of the pubic bones contributes to the acetabulum
the superior pubic ramus. The inferior pubic ramus contributes to the obturator foramen and ischiopubic ramus
Pubic arch
located immediately inferior to the pubic symphysis and formed by the paired ischiopubic rami.
Subpubic angle
The breadth of the pubic arch
Superior pelvic aperture
AKA Pelvic inlet. Divides the pelvis into an upper greater pelvis and a lower lesser pelvis. Delineated by pelvic brim
What forms the pelvic brim
sacral promontory, sacral ala, right and left linea terminalis
What forms linea terminalis
pubic crest, pecten pubis, arcuate line of ilium
Boundaries of major/greater pelvis
inferior boundary: superior pelvic aperture
lateral boundary: ale of ilium, iliac fossa and crests
posterior boundary S1 vertebrae
Pelvic outlet/inferior pelvic aperture bony landmarks
pubic symphysis, ischiopubic rami, ischial tuberosities, sacrotuberous ligaments, sacrum/coccyx
Muscular sheets that close off the inferior pelvic aperture
pelvic diaphragm, urogenital diaphragm
Minimum anteroposterior diameter (true conjugate)
extends from middle of sacral promontory to the posterosuperior border of the pubic symphysis. It is the narrowest fixed distance through which the baby’s head must pass in a vaginal delivery.
What is used to measure the true conjugate
diagonal conjugatel. Reach in to sacral promontory and mark where the pubic symphysis hits hand. Subtract 1.5-2 cm.
Location between the two farthest points on the pelvic brim
Transverse diameter, largest diameter in the pelvis
Distance from the sacroiliac joint to the contralateral iliopubic eminence
oblique diameter
Narrowest non-fixed part of the pelvic canal
interspinous distance
Sacrotuberous ligament
sacrum to ischial tuberosity, transforms sciatic notch to sciatic foramen
Sacrospinous ligament
Sacrum to ischial spine. Divides sciatic foramen into greater and lesser sciatic foramen.
What muscles cross from greater to lesser pelvis
NONE
Muscles of the lesser pelvis
piriformis, obturator internus, pelvic diaphragm levator ani, coccygeus
Muscle of levator ani
puborectalis, pubococcygeus, iliococcygeus
What surface does the piriformis form in the surface of the lesser pelvis
the inner deep surface of the lesser pelvis
What surface does the performs form in the surface of the lesser foramen
it forms the muscular wall for the anterolateral walls of the lesser pelvis
Tendinous arch of the pelvic diaphragm
Formed by deep fascia of obturator fascia.
What muscles form the pelvic diaphragm
Levator ani and coccygeus muscle. They meed on the midline at median raphe to form the pelvic floor. This separates the pelvic cavity from the perineum.
anterior boundary of perineum
pubic symphysis
anterolateral boundary of perineum
ischiopubic rami
lateral boundary of perineum
ischial tuberosities
posterolateral boundary of perineum
sacrotuberous ligaments
posterior boundary of perineum
inferior sacrum and coccyx
superior boundary of perineum
inferior aspect of pelvic diaphragm
Lateral boundary of ischioanal fossa
ischium and obturator internus muscle
medial boundary of ischioanal fossa
anal canal, external anal sphincter, and inferior surface of levator ani.
posterior boundary of ischioanal fossa
sacrotuberous ligament and gluteus maximus muscle
anterior boundary of ischioanal fossa
body of pubic bone
Base of ischioanal fossa
perianal skin
apex of ischioanal fossa
lies superiorly where elevator Dani muscles arise from obturator fascia
contents of ischioanal fossa
tough fibrous bands of connective tissue, fat, inferior rectal vessels and nerve, internal pudendal vessels, pudendal nerve.
Which component of the perineum is the pudendal canal located in?
It runs along the lateral wall of the ischio-anal fossa. It runs from the lesser sciatic notch and goes to the posterior edge of the perineal membrane.
